Shank construction



Patented Aug. 21, 1945 i UNITED STATES PATE NT OFFICE SHANI; CONSTRUCTION t `Walter B. Poble', Lynn, Mass. Application February 19, 1944, Serial'No. 523,164

4 Claims.

The present invention relates to tools and more I particularly to the shanks of tools such as drills,

end mills,` counterbores, reamers, reamer arbors,`

tools may be identical regardless of whether the shanks be of the taper `or straight types, and as a result it will be apparent that for the per- .forming of identical, oridentical size, operations on a drill `press and on a lathe, for examples,

atleast 'two tools of agiven size must be on,

hand,` differing only in their shank constructions.

` This situation necesarily doublesthe number of tools which ainachineY shop must keep in ltool inventory, since nearly all machine shops have both lathes land `drill presses, `and as a consequence the cost of` tool inventory is doubled.`

For a small'shop this item of rtoolcost may be a very important itern, but` it is also an importanti item where tool costs run into many thousands of dollars annually, as in larger shops.`

It is the principal object ofthe present invern`` tion to minimize tool cost to machine shops by providinga` shank construction which is receivable equally wel1,`. to give a few examples, by a lathe chuck or fby a collet, on the one hand, or by the spindle socket *of a drill press, on the 4other hand.

To the accomplishment `of.4 this object of such others as mayhereinafter appear, the various features or the present invention reside in certain constructions, combinations, and arrangements of parts all fully described herein-- their truescope in` after and then 'set forth in the appended claims, possessing advantages which will be in the art.

The various features `of the presentinvention will be readily understood from `reading this` specification" in the light of the accompanying drawing which illustrates the bestforms `of the invention at present known to Ithe inventor and in which:

readilyh apparent tothose skilled Fig. `2 is an enlarged detail View in elevation, similar to Fig. 1' but showing `a modified construction; l. Fig. 3 is a View of the Fig. 1 construction received `by the spindle socket of a drill press, the' spindle being shown in sectional detail;

Fig.`4 is a view of the Fig. lrconstru'ction received by a collet, the collet being shown partially in section and vwith its jaws in the gripping position they assume when the collet is mounted in a lathestock; and l Fig. 5 is a view of the Fig. 1 construction received by a three-javir chuck, the chuck being shown partially in section `to illustrate the gripping of the tool shank by the jaws.`

With reference to -the drawing, there is shown in Fig. `1 the shank portion of a drill, this type of tool being selected merelyfor purposes of illustration and explanation and not by way of limitationsince the shank portion shown may I be equally well used for an end mill, counterbore,`

reamer, Areamer arbor, shanked cutter, or the like.` The shank portion is' provided adjacent one end with a frusto-conical surfaced, or taper, portion I 0 and spacedtherefrom, and adjacent' thecuttingedgeor working portion II, with a second frusto-conical surfacedforftaper, portion I2. The mean diameter of the portion I2 is 'greater than that of the portion I0,` and the two frusto-conical surfaces aresurface portions of a cone of revolution and havethe same generatrix,`

I circular directrix, and vertex so that the frusto- Fig. `1 is an enlarged View in elevation of` the` shank portion of working portion lof commercial use.

conical surface of the portion I2 is, in effect, a continuation of the Truste-conical surface of the portion I0, i. e., is on the same taper.

Located between `the portions I0 and I2 and coaxial 'therewith is a cylindrical portion I3 of substantial length Vthe `diameter of which is shown in Fig. 1 as slightly larger than the diameter of the largerbase or 'bottom I4 of Vthe portion IIl but smaller than the diameter of the smaller base or top* I5 of the portion I2, with which it forms an annular shoulder I6, and 'located between the top of the cylindrical portion I3 and the lower base or bottom I4 of the portion IU there is preferably anV annular .I recess I1 the diameter of whichy is less than that ofthe base or bottom I4.` The top of the cylindrical portion I3 is preferably bevelled, as indicated at I8`, andthe constructionV is compiet d by a tongue or tang I9 at the top of the 4portion I0, but it is to be understood that `this tongue or` tang I9V may be `omitted since such` structureis not found on some taper Shanks in forming the recess I'I.

type, i. e.,

I3 would be'identioal in length with the Fig.-2 portion 22, and the Fig. 1 `line 25A would beas long as the Fig. 2 line 25, with the result thatthe upper end of the portion I3, while unbevelled, would touch in a circle the above imaginary frusto-conical surfacecon'sidered as extending between theportions I andiI2 and having their generatrix, circular directrix, and vertex. When, however, the bevelling I8 is provided, `the cylindrical surface of the portion I3 is` shortened by i an amount equal to the distance between the lines 25A and I8A, with the result that neither at the line IBA in Fig. 1 nor at any point between that lineand theshoulder I6 does any part ofthe portion I3 touch the above imaginary frustoconical surface. The practical and `benecial re-I sult of this construction will be demonstrated below in considering Fig. 3."

If it is not desired to make the Figs. vl or-2` ,constructions by a series of machining or work`" ing steps. a tool body having a rough shank may be supported and rotated and aforming tool` api plied to it during continued rotation,` the form'-,

ing tool being adapted to form in one machine operation only the frusto-conical and cylindrical surfaces above-described, orbeing adapted to form in one machine operation not only these surfaces but also the recess I'I, or being adapted to form in one machine operation the Fig. 1 surfaces I0, I2, I3, and alsoIB in addition to It will be seen that the above-described Figs. 1 and 2 disclosures, however manufacturedeach provide a, combined straight and taper shank ,coni struction in a single shank, as opposed to` a shank which is Wholly of thetaper type.` i. e., is wholly frusto-conical, or which is wholly of the straight is wholly cylindrical. 4 For examples' of uses of this combined shank construction, at.- tention is now called to Figs; 3, 4, and 5.

In Fig. 3 the shank `construction of 1 is shown received by the taper, i. e., frusta-conical,

socket 26 of a drill press `spindle 2l. The lspindle is provided with the usual way 28Ywhichjhas a driving function and also receives adrift or key (not shown), `and the taper of the `socket `2G is fthe same `as that of the portions I n and .I2`so that the tool shank as a whole is received in the socket 26 in a proper forced t in the usual I nan-l i ner and may be drifted therefrom.` ,'Ihejcylinjdrical portion I3 is wholly spaced from the wall of the socket 26 byreason of the bevellingfl.

as explained above, and as a consequence the wall of the socket 26 is engaged in the usual manner by the lateral surfaces of the portions I0 and I2 and hence rocking of the shank in the socket is prevented. If the Fig. 2 construction be forced into the socket 26, the cylindrical portion 22 will engage the wall of the socket only in 'a circle represented by the `line of merging (25) with the larger base or bottom of the frusto-conical portionZ, and there will be the same proper forced i'it of the portions 20 and 2| as referred to above in connection with the Fig. 1 portions I Il and I2. With either of the Figs. 1 and 2 constructions forced into the socket 26, it will be apparent that the function of the cylindrical portions I3 or 22 is to connect the frusto-conical surfaced portions I I) and I2, or 20 and 2|, respectively, and that the tool as a whole may be used in the customary manner.

In Fig.,4 the shank construction of Fig. 1 is shown gripped by the jaws 29 of a collet 30, the collet as a whole being shown in the position the customarymannen Y y The Fig: V21construction is 'entirely practicable jaws assume when mounted'ina lathe stock u(not shown) f andV in 'operative' condition. 'It will be noted that the jaws `29 gripv the cylindrical p01'- tion I3and `that'theirfront ends abutthe lshouls der4 I 6, `the portion I2l `extending `forwardly ofrthe jaws and the portion I0 extending'rearwardly of the gripping surfaces of the jaws,iand not engagingthem. Since the portion Il) tapersaway from the diameter of the portio'nI 3,31 iiie, since the diameter of thelarger'base ori-bottom I4 ofthe portion I0"s lless `than that of the portion I 3, as explained above, it will be apparent that the portion I0 would not .beengagedl by the gripping surfaces ofithe" javi/S29 evenV if they extended' cutting-edgeorworking porting of the tool. i With either type of shank`construction mounted in the jaws 29, it willbe clear that the tool as a whole may be'used in the customarynianner;

.l In Fig. 5 the shank construction of iFigrl 4is shownmounted in a' lathe chuck 3`I the sleeve 32 of which has Abeen rotated to causethering gear 33 to move thejaws 34 into clamping engagement with the portion I3` oftheshank construction. The jaws 34 abut the shoulder I6 and the'portion I2V extends `forwardly of the" jaws, "while the portion I Il extends rearwardlyof the rgripping surfaces of the 'jaws inthe direction of the hollow ofthe chuck body.' The jaws 34 do not engage the frusto-conicals'urfaced portion: I0 since it tapers away from the diameter of the portion `I3,f i; e., since the diameter of the larger base or bot` tom I4 ofthe portion I0 is lessfthanthat of the portion I3, and the above considerations would 4also-be true vwerethe' Fig; 2 shank construction gripped bythe jaws 34 since `the frusto`c onical portion 20 tapers away from the cylindrical por` tion"22. With either oftheFigs. 1 and-2 constructionsf mounted'in the jaws"34, however, it

` |2101'` 2 I `is to connect the cylindrical portions' hI3 or 22, respectively, with the cuttingl-edg'e'or working portion of the tool. With either type ofshank construction mounted inthe ljaws 34 itwill be clear that the tool asa whole may be Vused inthe for use with equipment whichis new and clean, but unfortunately under actual operating conditions in machine shops spindle sockets and the jaws of collets and chucks frequently `have dirt or other foreignmatter `onthem and if the equipment is old or worn chuck and collet jaws may have gripping surface irregularitiesthese conditions causing nicking, burring, or other distorting of the shank surfaces which they engage, and consequent danger of a tool shank being out of coaxiality with its machine drive.

The Fig. 1 construction minimizes the danger of this lack of coaxiality. When the recess I1 is provided, so that the diameter of the larger base or bottom I4 of the frusto-conical surfacedportion I0 is less than the diameter of the cylindrical portion I3, there is minimized any chance of dirt or other foreign matter or of surface irregularities on the gripping surfaces of the collet jaws 29 ,49: if. long erfthan shown, or on the; gripping, surfaces of thechuckjaw's 3,14.y (Figi 5);, engaging; the portionYV Ill; atv its 'base orL bottom |f4j and:v so distorting; itrthere; thus. causing: interference with a proper t of' the. portions Illrl andi l2 in a. socket suchzas 26... Stating the.foregoing'in dif'- ferentfwords; theformationiof the'recess H: causes collet vor chuck. jaws to clear the portion l0.' and thus not injure its: surface;

But ,the Fig. 1a construction alsol` provides. a fur"- ther factor of safetyin insuring a proper lit of' the portions Ml'V and I2; in a socket such as Z6. Since the bevel surfacef I84 causes the cylindrical surface of the-.portion I3 tf1-*beA shorter'than, thel portion 212, as? explained above, so that the recessadja'cent; end" (18A) of the: cylindricalsurface of. thel portion Ia^3 clears, i. e., lies within.. the taper of theportionsn l llano.- |.2-, asA alsof explained; above,

' thererisvminimized the danger oftV dirt orother'foreign matter on the1 wall:- of they socket 245:' engagingi the: portion If3and thus interfering.` with' a proper t in the'socket ofA the portions I0' and lf2. It

. may also be' pointedf out that thezbevelpsurfacey I84 performs a further safety functionl since it: mini mizes the dang-er of therecess-adiacent.end (.l 8A) of thef cylindrical: surface oftheportion I3 being distorteduponbeingbumpedrby the mouth of the is'.f'inserted` into'l the-Figs. 3;. 4;. or 5 constructions', in; a: directionitha-t. is not substantiallyI axiahthereof, with. the; same possible resultant interference` with. a. proper fit, of. theportions- Illy and If'2 in a socket such- `as- 2611.

WhileI` the` shank constructions illustrate-df; in Figs l. and. 2 havefbeen-` shown for' exemplary purposes as receivable by al drilly press spindle socket,A aa further. typefof taper socketA is that provided-by a. sleeve; or shell' drill socket-such: asi is'- frequently mounted..` in'y a lathe.' stock forrthel re"- ception of, a: taper'shanrk tool orv chuck., Shank.`

a particular physical embodiment. thereof, the.

scope -of itsapplication to-use inA connection with assaeia the: particular' structural details; herein: selected forv purposes, of explanation and.y illustration'. The particulars of construction herein lset forth are wellsuited to'. the particular physical embodimentsx of. the inventionwhich have beeneshown, Ibuttheinvention` is;v not` limited either to Athese features'con-jointly or to, these particulars. and. it is.- toY be understood that. they may be variously modifiedWithin` the skill.. of. the. artisan Withoutdeparting fromthe true scope oi-Y the actual invention-,. set, forth inl the following claims.

Whatis claimed as new is: y

L.. A1 shank construction characterized by two spaced frusta-conical surfacedportions one of- Which'hasalarger meandiameter than the other andbothof. which have the same generatrix, directrix,4 and vertex.,. andby arcylindrical:A portionI located between said two spaced. portions;, the dametenof. the cylindrical portion beingatr. least equal tothefdiameter of. the larger base of that spacedportion. having the smallerfmean diameter and being'smaller than. the, diameter. of.- the smaller base of. thatV spaced portonv `havingr thelargermean diameter. n f

2.y A shank construction characterized by two spaced. frustoFcon-ical. surfaced. portions one` et which hasa larger.` mean= diameter than the other and. both. at which have` the same generatrix,. directrix, andNe-rtex., andby acylindrical portion; located between.N said.` tvvoV spacedl portions the.

diameter 0f the `cylindrical portionbeing vgreater than the` diameter of the larger: base of, that spaced portion. havingthe smaller` mean diameterY and being smallenthan-the `diameter of theI smallerV base 'of thatspaced portion` having. the

larger mean diameter.,. the. diameter of the. cy lindrical portionbein-g notgreatenough to cause any portion. thereof. tmeXtend, outside vany ele` ment. otanimaginary frustofconicalzsurface comsidered asV extendingv between. said. tWof spacedi portionsfand having their. generati-ix, directrix, andfvertex..

3.r A shank construction such: asset forth:` in claim. 2 characterized by, the. presenceof: an. an nular recess located between. the cylindricaliportion, and that. spaced portion. having the. smaller. mean diameter. Y v

4;. A shank construction. such. as set. forth in: claim 2 characterized by the presence ofan anA nular recess located betweenthe cylindricalpor.- tion and thatspacedportion havingthe smaller mean diameter andby the, presence otabevelled. surface. at the4 end 'of the cylindrical surface. ad.- ja-centthe recess.

WALTER. B.. POI-ILE. 

